Radio base station, relay apparatus and radio communication method

Abstract

A radio base station determines a communication mode for each radio communication terminal from among a direct mode for communicating without via a relay apparatus, a relay mode for communicating via the relay apparatus by using a directional beam transmitted between the radio base station and the relay apparatus, and a combined mode for communicating by combining the direct mode and the relay mode based on the reception power information acquired from each radio communication terminal, and communicates with the each radio communication terminal by using the communication mode determined for the each radio communication terminal.

1 . A radio base station for forming a cell in which at least one relay apparatus is provided, comprising:
 an acquiring unit configured to acquire, from each radio communication terminal, reception power information of a first control signal received from the radio base station by the each radio communication terminal and reception power information of a second control signal received from the relay apparatus by the each radio communication terminal;   a communication mode determining unit configured to determine a communication mode for the each radio communication terminal from among a direct mode for communicating without via the relay apparatus, a relay mode for communicating via the relay apparatus by using a directional beam transmitted between the radio base station and the relay apparatus, and a combined mode for communicating by combining the direct mode and the relay mode, based on the reception power information acquired from the each radio communication terminal; and   a communication unit configured to communicate with the each radio communication terminal by using the communication mode determined for the each radio communication terminal.   
     
     
         2 . The radio base station according to  claim 1 , wherein the combined mode includes a capacity increasing mode for communicating with a radio communication terminal by the direct mode, while communicating with another radio communication terminal by the relay mode, by using a same radio resource. 
     
     
         3 . The radio base station according to  claim 1 , wherein the combined mode includes an area expanding mode for communicating with a radio communication terminal by both the direct mode and the relay mode by using a same radio resource. 
     
     
         4 . The radio base station according to  claim 1 , further comprising:
 an allocation unit configured to allocate a radio resource to the each radio communication terminal according to the communication mode determined for the each radio communication terminal.   
     
     
         5 . The radio base station according to  claim 4 , wherein when the communication unit is configured to communicate with a plurality of radio communication terminals via different relay apparatuses by the relay mode, the allocation unit is configured to allocate a same radio resource to at least one radio communication terminal selected from the plurality of radio communication terminals so that communication quality of each of the plurality of radio communication terminals meets a predetermined value. 
     
     
         6 . The radio base station according to  claim 4 , wherein the allocation unit is configured to coordinate communication modes for radio communication terminals to which the same radio resource is allocated between the radio base station and an adjacent radio base station. 
     
     
         7 . The radio base station according to  claim 1 , wherein the communication unit is configured to communicate with a radio communication terminal for communicating by the relay mode, via a plurality of relay apparatuses. 
     
     
         8 . The radio base station according to  claim 1 , wherein the communication unit is configured to communicate with a radio communication terminal for communicating by the relay mode, via a relay apparatus for transmitting and receiving same signal as that of the radio base station to/from another radio base station. 
     
     
         9 . A relay apparatus provided in a cell formed by a radio base station, comprising:
 a transmission unit configured to transmit a received signal that is amplified with a predetermined amplification factor by using a directional beam for the radio base station when the received signal from a radio communication terminal under the relay apparatus includes identification information of the relay apparatus, while transmitting a received signal that is amplified with a predetermined amplification factor to a radio communication terminal under the relay apparatus when the received signal from the radio base station includes identification information of the relay apparatus.   
     
     
         10 . The relay apparatus according to  claim 9 , further comprising:
 a loop interfering signal determining unit configured to determine whether or not reception power of a loop interfering signal in the received signal is a predetermined value or more; and   a frequency conversion unit configured to convert a frequency of the received signal into another frequency when the reception power of the loop interfering signal in the received signal is the predetermined value or more.   
     
     
         11 . A radio communication method in a radio communication system including a radio base station and at least one relay apparatus provided in a cell formed by the radio base station, comprising:
 in the radio base station, acquiring, from each radio communication terminal, reception power information of a first control signal received from the radio base station by the each radio communication terminal and reception power information of a second control signal received from the relay apparatus by the each radio communication terminal;   in the radio base station, determining a communication mode for the each radio communication terminal from among a direct mode for communicating without via the relay apparatus, a relay mode for communicating via the relay apparatus by using a directional beam transmitted between the radio base station and the relay apparatus, and a combined mode for communicating by combining the direct mode and the relay mode, based on the reception power information acquired from the each radio communication terminal; and   in the radio base station, communicating with the each radio communication terminal by using the communication mode determined for the each radio communication terminal.